Lex Mercatoria play a crucial role in resolving disputes arising from international trade contracts before arbitration bodies, thus establishing them as an independent legal system capable of regulating international commercial relations. This legal characteristic imposes a certain obligation on various arbitration bodies to apply them to the disputes brought before them, either based on the parties' intentions or based on the legal force inherent in those customs. Consequently, this research examines the extent of recognition of the binding force of commercial customs before arbitration bodies, and based on that, it elucidates the authority of these bodies in applying them to international trade disputes. It is evident that these customs, due to their flexibility derived from the nature of commercial transactions and the customary practices of traders resorting to them, have become today an independent legal system that imposes itself on arbitration bodies even if the parties did not choose to apply those customs. This paper recommends the Jordanian legislator to explicitly adopt the application of these commercial customs in the Jordanian Arbitration Law texts, following the example of national and international comparative legislation.